Yes. We do in Heavys in the military and I'm pretty sure most Airlines do too since I hear them relaying ELT info all the time. 121.5 or "Guard" is monitored at all times until something happens...if we hear an ELT, we report it, or if its a nuisance, we silence Guard for 10 minutes and hope it goes away. Guard saves your bacon, I've had the radio I was talking to ATC on fail, not know it, until they called us on guard.